Welcome to the North American Subaru Impreza Owners Club Wednesday May 27, 2015
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Click here to visit TireRack
Tire & Wheel Forum sponsored by The Tire Rack

Losing traction? Need new tires?
Click here to visit the NASIOC Upgrade Garage...
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Tire & Wheel

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 11-20-2004, 07:57 PM   #1
Columbo
Scooby Newbie
 
Member#: 17328
Join Date: Apr 2002
Location: Canyon Country, CA
Vehicle:
2002 WRX Wagon 4EAT
Appliance White

Default Vibration~shimmy

I got about 22k mile vibration-free miles from my S-03's. I WILL say that I had to go through 8 tires to find 4 that didn't have "run out". I recently switched to 16X7.5 SSR Comps and 225-50-16 GSD3's. I immediately noticed a front end shimmy (feel it and see it in the steering wheel). I rotated tires front-to-back and the vibration was less, but still there. I had them re-balanced and a 4-wheel alignment done. The tires did need re-balancing, but I think if you balance a tire, loosen and rotate the wheel on the machine, tighen and recheck, the balance will show it's off. And there can be variances between machines. The only thing "out of spec" on the alignment was the front toe. It was a little "out".

I went to yet another place who is familar with road force balancing. My tires ranged from 12-16 lbs of force. They did not feel this was a problem (under 20 lbs. they said was okay). Rebalance again, with road force adding about 1/4 oz. Still vibrates!!! You can't always see the steering wheel vibrating, but you can always feel it in your hands....and they get tingly and go numb!! The vibration is consistent (same frequency) as to wheel speed.

Quality rims. Quality tires. 90% freeway driving (daily commuter), no potholes, no curbs. Love to corner hard when I can though (hence the choice of tire). 56k miles on the car.

Absolutley nothing appears loose or worn in the front end suspension or steering......but it WILL be if this keeps up!

The only thing that comes to my mind...is the "run out" thing again. Balanced, yes....but because of the slight run out, the way the tires ride on the road, that's where the problem lies. No tech ever said anything about noticing run out, even though I asked them to look at it. Maybe "looks" are not enough.

Any helpful suggestions?

Thanks.
* Registered users of the site do not see these ads.
Columbo is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 11-21-2004, 02:33 AM   #2
WRXBob
Scooby Specialist
 
Member#: 12455
Join Date: Nov 2001
Location: CA
Vehicle:
02 WRX

Default

I have the same problem but with the 2 wheels, move them back and the shimy goes away. Did you take out the wheel and carefully retorque the wheels?
WRXBob is offline   Reply With Quote
Old 11-21-2004, 10:17 AM   #3
Columbo
Scooby Newbie
 
Member#: 17328
Join Date: Apr 2002
Location: Canyon Country, CA
Vehicle:
2002 WRX Wagon 4EAT
Appliance White

Default

I have 32 years of experience as a mechanic (12 of which were at new car dealerships). I was the first one to mount the wheels to the car. I used a Mac "click type" torque wrench (know to be accurate) set to 70 ft lbs. Hubs clean, wheels fit flush, threads good, it's all good! I retorqued a few days later. Rotating front-to back made little difference in the vibration. Since I rotate the tires everytime I change the oil and filter.....and for best tire wear, they all have to work on the front of the car. I now have over 1,500 miles on these tires, so any kind of "break-in" is alreay done.
Columbo is offline   Reply With Quote
Old 11-21-2004, 10:45 AM   #4
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Could it be that you are feeling the tread hitting the pavement and feeling a bit of tread squirm???

That or you have a bad tire(or 2/3/4)....
Uncle Scotty is offline   Reply With Quote
Old 11-21-2004, 11:39 AM   #5
Columbo
Scooby Newbie
 
Member#: 17328
Join Date: Apr 2002
Location: Canyon Country, CA
Vehicle:
2002 WRX Wagon 4EAT
Appliance White

Default

If there is a bad tire(s), then the vendor and 2 independents "overlooked" it/them....somehow. Balanced yes, but that's not enough. As for tire tread "hitting" the pavement, the vibration frequency is consistant with wheel speed...and independent of road surface. Smooth asphault feels/vibrates the same as concrete freeways with tar strips and expansion joints...with the latter being a harsher ride, of course. Of course I feel the little, independent jolts. That's not what I'm referring to. Like I said in a previous post, I DID have to go through 2 sets of S-03's to get 4 that were satisfactory. I don't look forward to going through that again...especially since there is no guarantee that I'll wind up with 4 good ones. Tire technology is supposed to be getting better....and we certainly DO have performance tires we never had before. Rims too. Cars are also getting better. Road force is a great idea, but didn't really become necessary until recently?? And "run out" is "run out" and there ain't no fix for that, right? Pehaps I'm a bit more sensitive to this because IAM a mechanic and know it's not right. Not acceptable to me.
Columbo is offline   Reply With Quote
Old 11-21-2004, 11:58 PM   #6
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Try a totally different kind of tires on you wheels...mebbe....I know that some places that say "It's in spec" just means that it's good enough for most, and maybe not good enough for someone with a finely calibrated 'butt dyno'.....make them 'zero' the wheels.

My 'butt dyno' seems to be calibrated a bit more finely than most and I feel/hear things that usually elude others....I've been accused of having 'bionic' hearing before ....and I know what ya mean on being sensitive to things....I'm an A&P, too
Uncle Scotty is offline   Reply With Quote
Old 11-22-2004, 06:16 PM   #7
Chunky_Chicken
Scooby Specialist
 
Member#: 9782
Join Date: Aug 2001
Location: Toronto, Ontario Canada
Vehicle:
2002 E46 M3
Laguna Seca Blue

Default

Columbo,

True shimmy cannot really be caused by a radial force variation. Shimmy is usually the result of poor dynamic balance or a high tangential force variation in the tire. A shake can be caused by high RFV.

A shimmy would be described as a rotational vibration of the steering wheel, where a shake would be a vertical vibration.

Would you say its definitely a shimmy or a combination of both. Putting your finger on the top of the steering wheel is the best place to be able to distinguish between the two.

-Pete
Chunky_Chicken is offline   Reply With Quote
Old 11-22-2004, 06:20 PM   #8
Columbo
Scooby Newbie
 
Member#: 17328
Join Date: Apr 2002
Location: Canyon Country, CA
Vehicle:
2002 WRX Wagon 4EAT
Appliance White

Default

It doesn't feel like the tires are not right for the car, just that they are not running "true". The GSP9700 reads "zero" for balance. Alignment was good too. ...I'm at a loss as to what to do. I liked the S-03's better, but I had some problems with those too. At least I was able to sort those out.

Shimmy. You can see the steering wheel rotate at a high frequency....equivelant to wheel rotation. No "shaking" of the dash, etc.

I've had tires be balanced, but have "run out" that caused this same shimmy. Picture a bent rim...."balanced", but not running true.

Last edited by Columbo; 11-22-2004 at 06:26 PM.
Columbo is offline   Reply With Quote
Old 11-23-2004, 11:31 AM   #9
2Stroke
Scooby Specialist
 
Member#: 36712
Join Date: May 2003
Location: RHE, SoCal
Vehicle:
2003 WRX Wagon
WRB

Default

Well, here are some suggestions about checking runout:

If you have a set of wheels & tires that are known good, you could put them on for a test. If the vibration disappears, you'll know for sure its either the tires or the wheels.

Whether you did the above or not, a dial indicator with a roller tip will allow you to check the radial runout or "out-of-roundness" at the tread, check the lateral runout by putting the indicator on the sidewall of the tire, and check the wheels for lateral runout as well. Checking wheels for radial runout requires removing the tires, unless you are willing to make assumptions about the bead surface being concentric to whatever surface you can reach. If you can reach a machined external surface near the bead, its usually a decent bet that its true to the bead surface, but it's still a bet.

Anything above about .050" radial and .030 lateral is cause for replacement of something, IMHO. Opinions vary widely here, that's just ball park numbers.

Runout of the wheels themselves will show up as tire runout as well. A perfect tire will have the same runout as the wheel its mounted on, but "amplified", if you will, due to the increased diameter at which measurement is made.

Here's a page that has good photos and a description of the process:

http://www.vibratesoftware.com/html_...ire_Runout.htm
2Stroke is offline   Reply With Quote
Old 12-13-2004, 10:14 PM   #10
Columbo
Scooby Newbie
 
Member#: 17328
Join Date: Apr 2002
Location: Canyon Country, CA
Vehicle:
2002 WRX Wagon 4EAT
Appliance White

Default

Good information. Thanks.

Okay, I returned the tires for "ride disturbance" and got S-03s instead. And even using the Hunter tire machine that is not supposed to touch the rim, there are lots of little marks and scrapes on the edge of the rim. Slight, but shouldn't be there at all. These guys work WAY too fast to be carefull! They just don't care. There is still a slight vibration in the steering wheel! Doesn't feel like a radial force variation, rather a lateral force one. Perhaps the "installers" are not "technicians", and doing something wrong (or not enough). They did not road force balance these even though they used the GSP9700 machine. One vendor told me that he doesn't sell aftermarket rims anymore because of problems such as the ones I have (and customers like me...ugh).

So, I'm wondering if the 7MM (per wheel) difference in offset could be causing the problem. Haven't ruled out a rim problem yet. Maybe the next step, dismounting the tire, but worried about more rim damage as well.

Last edited by Columbo; 12-13-2004 at 11:39 PM.
Columbo is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 09:23 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2015 Axivo Inc.
Copyright ©1999 - 2015, North American Subaru Impreza Owners Club, Inc.